In electroacoustic filters, electroacoustically active structures are arranged on a generally piezoelectric material. The electroacoustic structures are able to convert between electromagnetic RF (radio-frequency) signals and acoustic waves which are able to propagate in an acoustic track. In particular, electroacoustic filters may be designed as bandpass filters. Such bandpass filters allow desirable signals in a frequency range around a center frequency f to pass, i.e., their insertion loss at these passband frequencies is low. On the other hand, bandpass filters should block frequency components outside the passband. In other words, the insertion loss of filters at frequencies outside the passband is high.
Conventional RF circuits may comprise electrical matching circuits in order also to suppress certain undesirable frequency ranges via a zero point of the electrical matching circuit. Furthermore, it is possible to design electroacoustic devices which are electroacoustically inactive in a particularly sensitive frequency range.
Known measures for suppressing undesirable frequency components are disadvantageous in that the design flexibility, for example, in a matching network or in the design of the electroacoustic transducer, is limited. An additional problem is that measures for suppressing undesirable frequency components may degrade the frequency-dependent impedance of the corresponding transducer structures and/or matching networks.